Hull failure?

Carey,

Thank you so much for your response, but I am confused on a couple of items.

You state that hulls are make to flex evenly. But if you were to repair
these cracks by laying down a layer of Kevlar and then glass on top of this,
wouldn't that leave you with a large rigid area in an otherwise flexible
hull? To my mind, that would mean putting more stress on the adjacent
unreinforced sections of the hull, and causing more problems down the road
especially in the tandem canoe. As I stated below, the cracks in the
Dimension (16 feet WW OC2), are in front of the stern mini- cell pedestal
seat in the area of the center airbags, not end airbags. Again, to my mind,
this middle area for of the canoe probably flexes the most, and would not do
well being rigid in class 3-3+ drops.

Hopefully, I just don't understand the physics part correctly. Definitely
need to repair the boat properly as we hope to get many more years of use
out of it, especially since it isn't made anymore.

Carol.


"Carey Robson" <1.RemoveThis@CanoeBC.ca> wrote in message
news:LfXCi.122518$fJ5.78036@pd7urf1no...
> Most of my royalex boats have shown this kind of fatigue. I use them
> aggressively. the hulls are made to flex evenly and if there is no flex
> under the saddle that will develop cracks in behind it, especially if the
> boat has been trimmed stern heavy. I have also noted that cracks are more
> prevalent on a solo paddler's preferred paddling side.
>
> Their occurrence can be lessened, but not entirely eliminated, by securing
> a saddle to the bottom and not jamming it under a thwart.
>
> Repairing means adding weight to the boat. I now put a layer of 8oz Kevlar
> with a 5oz layer of glass on top across the bottom and effectively bathtub
> the bottom into the curved, (and stiffer), area of the sides. Unless the
> outside is cracked, I leave it alone. I don't believe the vinyl patch will
> be of any practical benefit. While I use Goop for a lot of soft material
> repairs, I think it will not be of any use here and indeed need to be
> removed prior to glassing. You can get many more yeas out of your boats -
> they will just be heavier.
>
> Sincerely,
> Carey Robson, www.CanoeBC.ca
> Master Instructor - Recreational Canoeing Association of British Columbia
>
>
> "Krueger" <dskrueger.RemoveThis@suddenlink.net> wrote in message
> news:zQKCi.27809$Pv4.17235@newsfe19.lga...
>> Has anybody come across this before?
>>
>> This spring, when we brought out our Dagger Dimension to be cleaned up
>> after winter storage, we noticed 2 cracks both about 4 inches long about
>> a foot in front of the stern pedestal seat about in the area where the
>> center airbags end. One crack went lengthwise, the other side to side.
>> There was no visible signs of damage on the outside hull. The last time
>> we had used the boat, last summer, we had not come down on any rocks in
>> that area that we could remember.
>>
>> Then this weekend while visiting our friend with a Dagger Genesis, he
>> showed us similar cracks in his boat. The first set were in the stern
>> under his airbags, both ran lengthwise and about 3 inches long. The
>> second set of cracks were just in front of his Bob Foote saddle, right
>> side, in the area where he would bail. These cracks were more of a star
>> pattern, but again, with both sets of cracks there wasn't any visible
>> sign on the outside of the hull of severe impacts. With the Genesis,
>> though, it had just come off of the Middle Fork of the Salmon where it
>> had been used and slightly abused. But it's also possible that these
>> cracks predated the trip, as the airbags had not been out of the boat
>> before the Middle Fork in over five years
>>
>> The Dimension is 18 years old, had been stored inside in a Sacramento,
>> California garage for the first 15 years, and basically wasn't used. We
>> purchased it in 2004 and store it in a shed in Eureka, north coast of
>> California (year-round temperatures average between high 30° to 60°), and
>> usually use it on one extended outing a year (for every day paddling, we
>> use a different Dimension-but that's a different story).
>>
>> The Genesis I believe was purchased in 1992, and is stored in Redding,
>> California (year-round temperatures average between high 30° to 100°
>> plus) outside, but out of the direct sun.
>>
>> So the big questions: Are these hulls starting to break down due to age?
>>
>> How best to repair them?
>>
>> On the Dimension , I cut large pieces of raft material and Vyna- bonded
>> them over the cracks. In the Genesis, he worked "Goop" into the cracks.
>> We would appreciate any input on how to deal with this if they continue
>> to appear..
>>
>> Thanks, happy paddling,
>>
>> Carol
>>
>> .
>>
>
>
 >> Stay informed about: Hull failure? 

>> So the big questions: Are these hulls starting to break down due to age?

Probably not. I have one boat, a Mohawk Challenger that is older and
it's in almost perfect shape. OTOH my XL-13 has a fair amount of damage
inflicted over the years. I'm not kind to these boats.
WRT flexing, the XL-13 had a square configuration of inside breakage
around stiff D-ring mounts I had installed. Basically I made that section
too rigid and the flex of the rest of the boat around that area ultimately
caused the cracks, much like bending a staple back & forth...

>>
>> How best to repair them?

The methods you used will not do the job very well. There will
still be too much flexion. I used the old 'classical' procedure for cracks
and it has held up well over a few years. Drill a small hole into the
royalex (but not through!) to relieve stress. Then with a knife vee out the
cracks and fill with epoxy resin. One called JB Weld is very good for
this -- it flexes just a bit. Be sure to thoroughly clean & degrease before
applying the epoxy. Then, cover with a layer of fiberglass cloth and make
sure it's thoroughly wetted with resin -- but use a minimal amount. Even
with a rounded ww hull those wide areas will flex which may cause other
cracks to develop. Plus, the presence of cracks make that flexion worse and
you'll get some oilcanning and the boat won't respond properly.

>>
>> On the Dimension , I cut large pieces of raft material and Vyna- bonded
>> them over the cracks. In the Genesis, he worked "Goop" into the cracks.

To some degree I am in favor of not creating stiff and flexing portions of
an expanse of royalex. This increases the likelihood of the "staple effect"
mentioned above. But here I think it will only delay the inevitable.

Hope this helps...

Joe P.

We
>> would appreciate any input on how to deal with this if they continue to
>> appear..
>>
>> Thanks, happy paddling,
>>
>> Carol
>>
>> .
>>
>
>
 >> Stay informed about: Hull failure? 

Hello,

You are welcome. Yes you will lose some of its flexibility but the
alternative is that the cracks will get bigger and hull integrity
sacrificed. I used the term bathtub and meant just that. Use a single piece
of 8 oz Kevlar with epoxy - not polyester resin. I use Industrial
Formulators, (now marketed by someone else - it cures down to 4 degrees C
and at 20 degrees gives you a working time of about 30 minutes). Remove your
saddle and all attachment points from one foot behind the saddle to about
two feet in front. Make a slightly oval shape from about 1 foot behind to
two feet in front of the saddle that reaches just into the curved area of
the bottom sides. Put a second piece of 3 to 5 oz glass on top that goes
past the edges of the first by about an inch. There are two reasons for
this: The first is that it graduates the stiffness and the second is that
Kevlar is very sharp and impossible to sand. The area in front of and behind
this is already fairly narrow and flexes less on a solo boat. On a tandem
boat you have to add more. Replace any rigid tie downs with flexible patch
D-rings. As far as preparing your boat: Wash it out well and dry thoroughly,
lightly sand with 80 or 120 grit, wipe out or blow out or wipe with
alcohol - do not use acetone or lacquer thinner - your are trying to
increase mechanical bond and these will melt the roughness that you have
just created.

Regarding two suggestions from Joe:
1. 3/8" stop holes drilled at the end of each crack. I also generally do
this.
2. cutting a V groove and filling with epoxy - is a bad idea, (experienced
based). It will not over the long term remain bonded. There is an argument
for doing an inverse V when the crack is on the outside.
3. As far as stiffness goes - people have been paddling glass boats for
years. They paddle better but are less forgiving on rocks.

Conclusion:
1. My oldest canoe is an Old Town Tripper that I purchased in 1979. It has
been across the Arctic Circle twice and on innumerable more southerly trips.
In the early years it was my only canoe and used extensively on grade 2 & 3.
It was partially wrapped and generally abused. This year I finally had to
glass most of the inside bottom - it gained weight - but who doesn't after
28 years.
2. I own and have repaired on numerous times 2 Old Town H2Pros, a tandemized
Blue Hole Sunburst. I also acquired another Old Town Tripper this year that
is 27 years old. It had been neglected but not abused and so aside from
replacing the wood gunnels and seats with vinyl/aluminum it has not required
and glass.
3. In the past I have owned and sold: a first glass boat, (keel and all), an
Old Town Penobscot, a Dagger Venture and a Blue Hole Starburst.

Sincerely,
Carey Robson, www.CanoeBC.ca
Master Instructor - Recreational Canoeing Association of British Columbia


"Krueger" <dskrueger DeleteThis @suddenlink.net> wrote in message
news:gY0Di.78$hP1.43@newsfe13.lga...
> Carey,
>
> Thank you so much for your response, but I am confused on a couple of
> items.
>
> You state that hulls are make to flex evenly. But if you were to repair
> these cracks by laying down a layer of Kevlar and then glass on top of
> this, wouldn't that leave you with a large rigid area in an otherwise
> flexible hull? To my mind, that would mean putting more stress on the
> adjacent unreinforced sections of the hull, and causing more problems down
> the road especially in the tandem canoe. As I stated below, the cracks in
> the Dimension (16 feet WW OC2), are in front of the stern mini- cell
> pedestal seat in the area of the center airbags, not end airbags. Again,
> to my mind, this middle area for of the canoe probably flexes the most,
> and would not do well being rigid in class 3-3+ drops.
>
> Hopefully, I just don't understand the physics part correctly. Definitely
> need to repair the boat properly as we hope to get many more years of use
> out of it, especially since it isn't made anymore.
>
> Carol.
>
>
> "Carey Robson" <1 DeleteThis @CanoeBC.ca> wrote in message
> news:LfXCi.122518$fJ5.78036@pd7urf1no...
>> Most of my royalex boats have shown this kind of fatigue. I use them
>> aggressively. the hulls are made to flex evenly and if there is no flex
>> under the saddle that will develop cracks in behind it, especially if the
>> boat has been trimmed stern heavy. I have also noted that cracks are more
>> prevalent on a solo paddler's preferred paddling side.
>>
>> Their occurrence can be lessened, but not entirely eliminated, by
>> securing a saddle to the bottom and not jamming it under a thwart.
>>
>> Repairing means adding weight to the boat. I now put a layer of 8oz
>> Kevlar with a 5oz layer of glass on top across the bottom and effectively
>> bathtub the bottom into the curved, (and stiffer), area of the sides.
>> Unless the outside is cracked, I leave it alone. I don't believe the
>> vinyl patch will be of any practical benefit. While I use Goop for a lot
>> of soft material repairs, I think it will not be of any use here and
>> indeed need to be removed prior to glassing. You can get many more yeas
>> out of your boats - they will just be heavier.
>>
>> Sincerely,
>> Carey Robson, www.CanoeBC.ca
>> Master Instructor - Recreational Canoeing Association of British Columbia
>>
>>
>> "Krueger" <dskrueger DeleteThis @suddenlink.net> wrote in message
>> news:zQKCi.27809$Pv4.17235@newsfe19.lga...
>>> Has anybody come across this before?
>>>
>>> This spring, when we brought out our Dagger Dimension to be cleaned up
>>> after winter storage, we noticed 2 cracks both about 4 inches long about
>>> a foot in front of the stern pedestal seat about in the area where the
>>> center airbags end. One crack went lengthwise, the other side to side.
>>> There was no visible signs of damage on the outside hull. The last time
>>> we had used the boat, last summer, we had not come down on any rocks in
>>> that area that we could remember.
>>>
>>> Then this weekend while visiting our friend with a Dagger Genesis, he
>>> showed us similar cracks in his boat. The first set were in the stern
>>> under his airbags, both ran lengthwise and about 3 inches long. The
>>> second set of cracks were just in front of his Bob Foote saddle, right
>>> side, in the area where he would bail. These cracks were more of a star
>>> pattern, but again, with both sets of cracks there wasn't any visible
>>> sign on the outside of the hull of severe impacts. With the Genesis,
>>> though, it had just come off of the Middle Fork of the Salmon where it
>>> had been used and slightly abused. But it's also possible that these
>>> cracks predated the trip, as the airbags had not been out of the boat
>>> before the Middle Fork in over five years
>>>
>>> The Dimension is 18 years old, had been stored inside in a Sacramento,
>>> California garage for the first 15 years, and basically wasn't used. We
>>> purchased it in 2004 and store it in a shed in Eureka, north coast of
>>> California (year-round temperatures average between high 30° to 60°),
>>> and usually use it on one extended outing a year (for every day
>>> paddling, we use a different Dimension-but that's a different story).
>>>
>>> The Genesis I believe was purchased in 1992, and is stored in Redding,
>>> California (year-round temperatures average between high 30° to 100°
>>> plus) outside, but out of the direct sun.
>>>
>>> So the big questions: Are these hulls starting to break down due to age?
>>>
>>> How best to repair them?
>>>
>>> On the Dimension , I cut large pieces of raft material and Vyna- bonded
>>> them over the cracks. In the Genesis, he worked "Goop" into the cracks.
>>> We would appreciate any input on how to deal with this if they continue
>>> to appear..
>>>
>>> Thanks, happy paddling,
>>>
>>> Carol
>>>
>>> .
>>>
>>
>>
>
>
 >> Stay informed about: Hull failure? 

Thank you everybody for your advice. It seems like I should have asked for
it before I did my patch job, I've got some work ahead of me.

Happy paddling,

Carol.


"Joe Pylka" <jpylka.TakeThisOut@earthlink.net> wrote in message
news:13dpr3bjprja76@corp.supernews.com...
>>> So the big questions: Are these hulls starting to break down due to age?
>
> Probably not. I have one boat, a Mohawk Challenger that is older and
> it's in almost perfect shape. OTOH my XL-13 has a fair amount of damage
> inflicted over the years. I'm not kind to these boats.
> WRT flexing, the XL-13 had a square configuration of inside breakage
> around stiff D-ring mounts I had installed. Basically I made that section
> too rigid and the flex of the rest of the boat around that area ultimately
> caused the cracks, much like bending a staple back & forth...
>
>>>
>>> How best to repair them?
>
> The methods you used will not do the job very well. There will
> still be too much flexion. I used the old 'classical' procedure for
> cracks and it has held up well over a few years. Drill a small hole into
> the royalex (but not through!) to relieve stress. Then with a knife vee
> out the cracks and fill with epoxy resin. One called JB Weld is very good
> for this -- it flexes just a bit. Be sure to thoroughly clean & degrease
> before applying the epoxy. Then, cover with a layer of fiberglass cloth
> and make sure it's thoroughly wetted with resin -- but use a minimal
> amount. Even with a rounded ww hull those wide areas will flex which may
> cause other cracks to develop. Plus, the presence of cracks make that
> flexion worse and you'll get some oilcanning and the boat won't respond
> properly.
>
>>>
>>> On the Dimension , I cut large pieces of raft material and Vyna- bonded
>>> them over the cracks. In the Genesis, he worked "Goop" into the cracks.
>
> To some degree I am in favor of not creating stiff and flexing portions of
> an expanse of royalex. This increases the likelihood of the "staple
> effect" mentioned above. But here I think it will only delay the
> inevitable.
>
> Hope this helps...
>
> Joe P.
>
> We
>>> would appreciate any input on how to deal with this if they continue to
>>> appear..
>>>
>>> Thanks, happy paddling,
>>>
>>> Carol
>>>
>>> .
>>>
>>
>>
>
>
 >> Stay informed about: Hull failure?